The present invention relates to a method and apparatus for rotatable display apparatus, and more particularly to a display apparatus including a rectangular screen having short and long sides capable of being rotated between a position in which the short side lies horizontally and a position in which the long side lies horizontally, and suitable for displaying images having different width/height ratio.
A so-called filing system has been practically used in order to meet the requirements of rationalizing office works. With a filing system, a great amount of image data for images, documents and the like are read with an image scanner or the like and stored in a storage device such as an optical disk or magnetic disk so that the image data can be processed, retrieved, renewed, printed out and so on at any time as desired.
As the image data to be stored in a storage device of such a filing system, not only the document data having relatively similar formats, but also the mixed data of such documents with drawings, photographs and the like having relatively various types of formats, e.g., a longer height or width of image frame, are stored in many cases.
If an ordinary display having a fixed ratio of width to height is used for displaying such image data stored in a storage device so as to renew or check the contents thereof, a portion of the image data may be displayed outside of the screen or a blank portion may be a part of the screen image.
U.S. Pat. No. 4,542,377 (corresponding to JP-A-50-123880), discloses display apparatus arranged to be rotatable so that an operator manually rotates, if necessary, the display apparatus by 90 degrees to obtain a ratio of width to height of the screen image suitable for the number of characters per line of the character data to be displayed.
Generally, a display apparatus for use in a filing system adapted to be usable not only for documents but also for images is a large CRT of 17 inches or greater which can display thereon an image of about A-4 size. Therefore, the conventional method of switching the width/height ratio by manually rotating the display apparatus burdens an operator with large power, thereby deteriorating workability.
Furthermore, if it is necessary that the image data of plural pages having different width/height ratios be sequentially displayed to perform some works, the operator is required to visually check the displayed image data whether or not the display screen is to be rotated for that image data. It is practically impossible for the operator to smoothly and immediately respond to a width/height ratio change of the sequentially displayed image data and rotate the display screen.